Investigations will be continued on the mechanism of action of ethanolamine ammonia-lyase, an adenosylcobalamin-dependent enzyme. Analogs of the substrate will be tested for their effect on the enzyme-cofactor complex for the purpose of establishing the mechanism of amino group migration. Attempts will be made to inactivate the enzyme and label the active site by means of affinity labels as well as non-specific inactivating agents. Structural studies will be undertaken to further define the quaternary structure of the enzyme and to investigate the roles of the various subunits in the catalytic process.